Effect of Processing on the Tensile Properties of Coir Fiber for Sustainable Composite Development

Sustainable materials based on agricultural waste contribute to a sustainable world and circular economy. Natural materials in the form of fibers and particles have a complex architecture and chemical composition compared to synthetic materials and require special processing for use in engineering applications. Coconut Fiber, called coir, is available in huge quantities and is reported to have superior mechanical properties. Various physical and chemical methods are adopted to modify the coir fiber surface to improve performance, wettability, and bonding with the polymer matrix. The effect of process conditions and moisture level on fiber strength is reported. The alkaline treatment with 5% NaOH modified the fiber’s surface and enhanced the fiber’s wettability with the polymer matrix. The tensile strength is increased after alkaline treatment and oven drying. In the alkaline treatment, with the removal of lignin, crystallinity of the fiber increases, and the reorientation of the cellulose microfibrils strengthens the fiber. Oven-dried coir fiber shows an increase in strength due to the shrinkage, entanglement, and cross-linking of the microfibrils.